/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/VoiceInterface.h
This returns the current amplitude of a given player's incoming audio.
-1.0 if the PlayerId was not found or if this isn't supported with the current Voice Interface, and a value from 0.0 to 1.0 otherwise.
virtual float GetAmplitudeOfRemoteTalker ( const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) & PlayerId )